To prevent failure in case of end zone reinforcement of corner zones, where spalling or secondary tension develops at corners, hair pin bars of suitable steel should be provided, while designing formwork, use of cap cables must be considered and space provided for fixing and handling hydraulic jack must be sufficient especially at soffits of beam when cap cables are used.

Hoyer has developed an expression for computing transmission length, based on wedge action: L_t = ?/2? (1+?_c) (?_c/?s-f_pi/E_c) (f_pe/2f_pi-f_pe), L_t = transmission length, ? = wire diameter, ? = coefficient of friction between steel and concrete, ?_c = Poisson?s ratio for concrete, ?_s = Possion?s ratio of steel, ?_c = modular ratio (E_s/E_c), E_c = modulus of elasticity of concrete of concrete, f_pi = initial stress in steel, f_pe = effective stress in steel.

The effective prestressing force of 75 to 80 percent develops to about half of transmission length, 90 to 95 percent of prestressing force is attained at about three fourths of transmission length from end face of beam.

Lt = ((f_cu)1/2 x 10³/?)^1/2 = Transmission length,
7mm diameter smooth wires, ? = 0.0174, f_cu = 42n/mm², L_t = ((42)^1/2 x 10³/ 0.0174) = 610mm = 87?.

The creep coefficient varies from 1 to 3 and it is denoted by ?, composite section carries all applied loads when effect of creep is more and on precast element cast in situ slab is casted in which slab has already undergone shrinkage and creep, but creeping starts only after e in situ slab is casted and is larger due to wet concrete and both precast beams and cast insitu slabs contains differential creep and shrinkage which induced stresses from one element to anor element.

Based on tests conducted according to Marshall using wires of 2 and 5mm diameter stressed to 1575 and 1100n/mm² respectively in conjunction with a concrete having cube strength of 80n/mm², values of maximum bond stress and constant ? found to be 7.42n/mm² and 0.00725 respectively.

Along with deformed bars, loops, hooks or right angle bends are necessary in case of short bond lengths; about half of total reinforcement is preferably located within a length equal to one third of transmission length from end, rest being distributed in remaining distance.

Bond stress at intermediate points is resisted by adhesion and in transfer zone adhesion is destroyed by invariable slip and sink of tendons into concrete, transversely ribbed steel type of wire has a diameter of 20 to 40 mm2 area of bond length 500mm.

The area at or near centroidal sections of end faces of beams have maximum tensile stress and if tensile stresses exceed tensile strength of concrete, horizontal cracking occur, mid span of section effects deflection parameters of structural member.

The zone of transverse compression attains maximum bond stress and when bond stress becomes zero various changes occur, 2 or 3 strand wire of diameter 2 to 3 has a bond length of 700mm, 7 wire strand of diameter 2 to 4 has a bond length of 1000mm.